In northern climates, snowfall often accumulates in large quantities on the roofs of buildings. The heat in the interior of the building will escape through the attic and the roof, especially if the insulation in the attic is inadequate or the attic is poorly ventilated as is often the case. This heat will melt the bottom of the snow pack on the roof creating a layer of water that runs down the roof to the eaves beneath the snow pack. This water will refreeze along the eaves and create what is known as an "ice dam", namely a long ridge of ice along the eaves protruding upwardly from the eaves.
Such an ice dam is detrimental because it traps melted water behind it. This water will often be forced beneath the shingles on the roof into the interior of the building where it can cause damage to the ceilings or walls of the building. It is obviously expensive to repair such damage. Thus, much time and effort is often spent either removing ice dams from roofs or trying to prevent their creation.
One way of attempting to deal with ice dams is to let them form and then to periodically remove them by thawing or chipping them out. This is a labor intensive process which at the least is inconvenient and difficult to do and can be quite expensive to have done if workmen are hired to do it. In addition, since an ice dam typically adheres to the eaves of the roof very tightly, known methods of removing such ice dams can easily damage the roof itself. Moreover, it can be dangerous to attempt to remove such ice dams as it is often necessary to walk on the roof to do so, giving rise to the possibility of falling off the roof and injuring oneself.
A better method of dealing with ice dams is to prevent their formation in the first place. Various devices have been developed for doing this. For example, electrical heating tape or cords have been used spread in a serpentine fashion along the eaves to create channels in the ice dam to allow drainage of the melted water behind the dams through such channels. In addition to the obvious expense of the electricity required to keep such tape or cords heated, they are not very effective for their intended task. While they may initially create some channels that drain some water, these channels soon ice up rather completely until the tape or cord is itself completely encased in the ice dam with the channels having disappeared.
The most effective way of preventing ice dam formation is to physically remove the snow from those portions of the roof adjacent the eaves, i.e. in a band or strip of the roof beginning at the eaves and extending upwardly for at least a few feet. This is sometimes done by climbing onto the roof and using a shovel to shovel the snow off. This method again can be somewhat dangerous due to the possibility of falling off the roof. In addition, this method is limited to roofs which are fairly easy to climb onto.
A device known as a roof rake has been developed to facilitate removal of the snow from a roof without having to climb onto the roof. This roof rake is used by a person standing on the ground adjacent the building or on a ladder that is propped up against the side of the building. The roof rake typically includes a planar snow moving member having a substantially vertical snow moving face or surface. A long handle assembly is connected to the snow moving member to allow the snow moving member to be held and manipulated by the user. Some roof rakes have various extension members for extending the handle assembly to a total length that may be 20 or 30 feet or even more.
In using a roof rake of this type, the user will hold the handle assembly, which is many feet long, and will raise the snow moving member until it is positioned over the roof and is located a few feet inwardly of the eaves. The user will then allow the snow moving member to drop down onto the surface of the roof. The user will then pull on the handle to move the snow moving member towards him. As this is done, a swath of snow is pulled forwardly by the roof rake over the edge of the roof. The process is then repeated for adjacent swathes until the snow has been cleared from a desired section of the roof.
While roof rakes of the type just described are effective in moving snow from roofs and thus in preventing the formation of ice dams, the Applicants have found that they can damage the surface of the roof. The snow moving surface of the roof rake includes a relatively sharp lower edge that simply directly engages against the roof. As the snow moving member is pulled forwardly during operation of the roof rake, this edge scrapes against the surface of the shingles of the roof, thus scraping off some of the gravel or other particulate material that forms the water repelling face of the shingles. At the conclusion of a winter season in which a roof rake is used on a roof over a number of times, the Applicants have found a layer of this particulate material in the gutters along the eaves.
Obviously, the damage done to a roof by a conventional roof rake is a disadvantage of using such a device. Such damage will eventually cause the roof to leak and damage the interior of the building. At the least, the damage will shorten the life of the roof, requiring it to be replaced earlier than would otherwise have been necessary.